<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  
</head>
<body>
  <div id="app">
    <!-- 不要下标 -->
    <ul>
      <li v-for="item in arr">
        {{ item }}
      </li>
    </ul>
    <!-- 循环得到下标 -->
    <ul>
      <li v-for="(item, index) in arr">
        {{ item }}
        ——>
        {{ index }}
    </ul>

    <!-- 循环对象 -->
    <ul>
      <li v-for="(value,key, index) in json">
        {{ value }}
        ——>
        {{key}}
        ——>
        {{index}}
      </li>
    </ul>
  </div>
  <script src="./vue.js"></script>
  <script>
    // 定义vm
    const vm = new Vue({
      el: '#app',
      data: {
        arr: ['a', 'b', 'c', 'd'],
        json: {
          name:"小明",
          age:18,
          gender:"男"
        }
      }
    })
  </script>
</body>
</html>